package com.servitization.commons.util.crypto;

/**
 * Block cipher engines are expected to conform to this interface.
 */
public interface BlockCipher {
    /**
     * Initialise the cipher.
     *
     * @param forEncryption if true the cipher is initialised for encryption, if false for
     *                      decryption.
     * @param params        the key and other data required by the cipher.
     * @throws IllegalArgumentException if the params argument is inappropriate.
     */
    void init(boolean forEncryption, CipherParameters params)
            throws IllegalArgumentException;

    /**
     * Return the name of the algorithm the cipher implements.
     *
     * @return the name of the algorithm the cipher implements.
     */
    String getAlgorithmName();

    /**
     * Return the block size for this cipher (in bytes).
     *
     * @return the block size for this cipher in bytes.
     */
    int getBlockSize();

    /**
     * Process one block of input from the array in and write it to the out
     * array.
     *
     * @param in     the array containing the input data.
     * @param inOff  offset into the in array the data starts at.
     * @param out    the array the output data will be copied into.
     * @param outOff the offset into the out array the output will start at.
     * @return the number of bytes processed and produced.
     * @throws IllegalStateException if the cipher isn't initialised.
     */
    int processBlock(byte[] in, int inOff, byte[] out, int outOff)
            throws DataLengthException, IllegalStateException;

    /**
     * Reset the cipher. After resetting the cipher is in the same state as it
     * was after the last init (if there was one).
     */
    void reset();
}
